In electrical power networks comprising renewable generation plants, such as wind power generation plants, network utilisation of the generation plants tends to be low because of conservative assumptions about available power and network loading. Typically, in a network comprising wind power generation plants, which may include wind farms, the amount of wind generating capacity that is permitted to be connected to the network is limited by the condition in which wind generation is high and network loading is low, which results in worst case power flow into the network and voltage rise. The worst case condition particularly affects the area here defined as the electrical route.
As used herein the term ‘generation plant’ encompasses any apparatus for generating electrical power. A generation plant may comprise a single generator. Alternatively a generation plant may comprise a plurality of generators in a cluster controlled together, such as for example a wind farm. Alternatively, a generation plant may comprise a plurality of clusters of generators, such as for example a plurality of wind farms at separate locations within an electrical power network.
As used herein the term ‘electrical route’ encompasses any electrical connection between a generation plant and a bulk electrical power network. The electrical route may for example be a transmission or distribution line. There may be one or more additional generation plants and/or load connections along an electrical route. The electrical route may have a number of technical limits restricting the transfer of power from a generation plant to a bulk electrical power network.
As used herein, the term ‘bulk electrical power network’ encompasses the part of the wider electrical power network separate to the generation plant and the electrical route. The bulk electrical power network may be termed a ‘stronger’ part of the network relative to the electrical route. That is, the bulk electrical power network is able to accept larger power transfer than may be handled by the electrical route.
If network loading is low and wind generation power is high then the power from the wind generation plant may overload and/or provoke voltage rise in parts of the electrical route. Therefore, in known electrical power networks the declared nominal capacity of the wind power generation plant is limited such that overload or excessive voltage rise issues do not arise under the worst case conditions.
Generally, the coincidence of high wind and low load seldom occurs.
There have been attempts to take detailed real-time measurements in the network and derive less conservative constraints in a centralised process. However, these attempts have not been widely adopted because they might require the installation of a large number of real-time measurement devices and associated communications channels.